Catch forecasting and relationship between water temperature and catch fluctuations in snow crab Chionoecetes opilio in the western Sea of Japan

Abstract

Catch forecasting and the relationship between water temperature and catch in the snow crab Chionoecetes opilio in the western Sea of Japan were investigated. Catch was used as an index of abundance on the basis of high correlations between catch per unit effort for the period when the latter data were available. The pattern of fluctuations in catches and index coincided well with each other. Therefore, catch data were regarded as an index of abundance and the correlation coefficient between catch and water temperature was calculated at several depths from 1964 to 1999. Catch forecasting models were composed using significantly correlated variables with the following results: (i) in April and September, the catch showed high positive correlation with water temperatures (depth 50, 100, and 200 m, time lag 4-6 years); and (ii) a model using water temperatures in April alone (depth 100 m, time lag 4-7 years) forecasted the catches with a coefficient of determination of 0.504, where models using more variables (water temperatures in the 2 months and catches) showed a coefficient of 0.587 at most. Environmental conditions during the early life stages of the snow crab are thought to deeply influence the fluctuations in abundance.KEY WORDS: catch forecasting, Chionoecetes opilio, mechanism of catch fluctuation, snow crab, water temperature, western Sea of Japan.

A Common Concept of Population Dynamics Applicable to Both Thrips imaginis (Thysanoptera) and the Pacific Stock of the Japanese Sardine(Sardinops melanostictus)

“…This indicates that the population size in month i could be determined in proportion to the population size in month i-1, i.e., the relationship between the populations sizes in month i and that in month i-1 can be expressed using a simple proportional model. The validity of a proportional model is not explicitly noted, however, the fluctuations of the catches in the species such as snow crab [22], sandfish [23,24] and walleye pollock [25] are already explained without assuming a density-dependent effect in the fluctuation mechanism in catches. The (4).…”

Interannual-decadal variability of demersal fish assemblages in the Tsushima Warm Current region of the Japan Sea: Impacts of climate regime shifts and trawl fisheries with implications for ecosystem-based management

“…It covers a wide range of the ocean from coastal waters to offshore deep waters and targets almost all of the commercially-important demersal species from warm-water to cold-water species (Misu, 1974;Ogata, 1980). Large interannual fluctuations in the catches of the main target species of the trawl fishery, such as flathead flounder, snow crab and sandfish (Arctoscopus japonicus) have been shown to be associated with water temperature (Moriyama and Adachi, 2002;Watanabe et al, 2006;Yamanaka et al, 2007). However, only a few studies have focused on the variations in demersal fish assemblages in the Japan Sea (Nishimura, 1966;Moriwaki and Ogawa, 1989).…”